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ares_library_cleanup(3) [centos man page]

ARES_LIBRARY_CLEANUP(3) 				     Library Functions Manual					   ARES_LIBRARY_CLEANUP(3)

ares_library_cleanup - c-ares library deinitialization SYNOPSIS
#include <ares.h> void ares_library_cleanup(void) cc file.c -lcares DESCRIPTION
The ares_library_cleanup function uninitializes the c-ares library, freeing all resources previously acquired by ares_library_init(3) when the library was initialized, provided there was only one single previous call to ares_library_init(3). If there was more than one previous call to ares_library_init(3), this function uninitializes the c-ares library only if it is the call matching the call to ares_library_init(3) which initialized the library (usually the very first call to ares_library_init(3)). Other calls to ares_library_cleanup(3) have no effect other than decrementing an internal counter. This function must be called when the program using c-ares will no longer need any c-ares function. Once the program has called ares_library_cleanup(3) sufficiently often such that the library is uninitialised, it shall not make any further call to any c-ares func- tion. This function does not cancel any pending c-ares lookups or requests previously done. Program must use ares_cancel(3) for this purpose. This function is not thread safe. You have to call it once the program is about to terminate, but this call must be done once the program has terminated every single thread that it could have initiated. This is required to avoid potential race conditions in library deinitial- ization, and also due to the fact that ares_library_cleanup(3) might call functions from other libraries that are thread unsafe, and could conflict with any other thread that is already using these other libraries. Win32/64 application DLLs shall not call ares_library_cleanup(3) from the DllMain function. Doing so will produce deadlocks and other prob- lems. AVAILABILITY
This function was first introduced in c-ares version 1.7.0 along with the definition of preprocessor symbol CARES_HAVE_ARES_LIBRARY_CLEANUP as an indication of the availability of this function. Reference counting in ares_library_init() and ares_library_cleanup(), which requires calls to the former function to match calls to the latter, is present since c-ares version 1.10.0. Earlier versions would deinitialize the library on the first call to ares_library_cleanup(). Since the introduction of this function, it is absolutely mandatory to call it for any Win32/64 program using c-ares. Non-Win32/64 systems can still use c-ares version 1.7.0 without calling ares_library_cleanup(3) due to the fact that currently it is nearly a do-nothing function on non-Win32/64 platforms. SEE ALSO
ares_library_init(3), ares_cancel(3) AUTHOR
Yang Tse Copyright 1998 by the Massachusetts Institute of Technology. Copyright (C) 2004-2009 by Daniel Stenberg. 19 May 2009 ARES_LIBRARY_CLEANUP(3)

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ARES_GET_SERVERS(3)					     Library Functions Manual					       ARES_GET_SERVERS(3)

ares_get_servers - Retrieve name servers from an initialized ares_channel SYNOPSIS
#include <ares.h> int ares_get_servers(ares_channel channel, struct ares_addr_node **servers) DESCRIPTION
The ares_get_servers(3) function retrieves name servers configuration from the channel data identified by channel, as a linked list of ares_addr_node structs storing a pointer to the first node at the address specified by servers. Function caller may traverse the returned name server linked list, or may use it directly as suitable input for the ares_set_servers(3) function, but shall not shrink or extend the list on its own. Each node of the name server linked list is stored in memory dynamically allocated and managed by c-ares. It is the caller's responsibility to free the resulting linked list, using ares_free_data(3) , once the caller does not need it any longer. This function is capable of handling IPv4 and IPv6 name server addresses simultaneously, rendering ares_save_options(3) with optmask ARES_OPT_SERVERS functionally obsolete except for IPv4-only name server usage. RETURN VALUES
ares_get_servers(3) may return any of the following values: ARES_SUCCESS The name servers configuration was successfuly retrieved ARES_ENOMEM The memory was exhausted ARES_ENODATA The channel data identified by channel was invalid. SEE ALSO
ares_set_servers(3), ares_init_options(3), ares_save_options(3) AVAILABILITY
ares_get_servers(3) was added in c-ares 1.7.1 AUTHOR
Implementation of this function and associated library internals are based on code, comments and feedback provided in November and December of 2008 by Daniel Stenberg, Gregor Jasny, Phil Blundell and Yang Tse, December 2009 by Cedric Bail, February 2010 by Jakub Hrozek. On March 2010 Yang Tse shuffled all the bits and this function popped out. Copyright 1998 by the Massachusetts Institute of Technology. Copyright (C) 2008-2010 by Daniel Stenberg 5 March 2010 ARES_GET_SERVERS(3)
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